378 STATE BOARD OF AGRICULTURE. 



Months. Per Cent of Drainage to Rain-Fall. 



January, February, March, April 16.5 per cent. 



May, June, July, August 4.3 per cent. 



September, October, November, December 26.2 per cent. 



Mr. Dickinson, of England, found that the discharge, as compared with 

 the rainfall, was, from October to March, 75 per cent; from April to 

 September, eight per cent; average 41.5 per cent. Mr. Tracy, of Boston, 

 concluded that it varied from 44 to 45 per cent. Experience seems to show 

 that if drains be made of a capacity sufficient to convey off half ail inch of 

 rainfall each day of twenty-four hours, they will give excellent results in 

 practice, and it has also been shown that if sizes much smaller be used, the 

 results are not satisfactory. To use larger tiles than such as are necessary, is 

 extravagant; tiles should also run full at certain times in the year, in order to 

 be flushed out. The following table for sizes of tile is very carefully com- 

 puted, each acre being considered the equivalent to 1,815 cubic feet of water, 

 which is an amount just sufficient to cover one acre witii water half an inch 

 in depth. This amount would weigh about 471 tons ; consequently a system 

 of tile drains would have a carrying capacity of 4,750 tons for each acre 

 drained for each one hundred days. As regards the use of the table for the 

 capacity of drains, I would say that no doubt in many cases, smaller tiles 

 than the sizes indicated by the table would answer, for the reason that only a 

 system of random or casual drainage is intended. The table will answer for 

 thorough drainage in regions where the rainfall is no greater than in southern 

 Michigan, and thorough drainage indicates at least the conveying otf of 

 the water within tAventy-four hours. If only a few drains are used, the water 

 would be longer in reaching the drains, and consequently more acres could be 

 cared for. The probability is, however, that at some time thorough drainage 

 will be required on the land, and as the digging is the most expensive part of 

 drainage, tile large enough for thorough drainage had better be put in, and a 

 permanent job completed, as far as may be, rather than to do what must be 

 done over again. 



As regards the practice of tile-laying, I would say, that both in this country 

 and in England, it is customary to lay larger tile than formerly. In England 

 tiles as small as one inch have been largely used, and are still used to a con- 

 siderable extent, while 2f and three-inch are considered quite large tile. In 

 this country there is a growing prejudice against the use of tile smaller than 

 three-inches, and the majority of tile-makers are not making smaller sizes. 

 In my opinion, this prejudice against smaller tile is unreasonable, and due 

 principally to the fact that drains of small tile, if carelessly laid, are more 

 likely to fail than larger ones. Thus, for example, a variation of two inches 

 from the grade line would> in time, be fatal to a two-inch drain, whereas, it 

 would only partially choke up a three-inch drain. 



The reason two-inch pipes have failed utterly is, no doubt, due to careless 

 construction. I claim that there are many places in a system of drainage 

 when these tiles, properly laid, will answer every purpose. I know that a few 

 .years ago, expectations, that were never realized, were aroused by enthusi- 

 asts in drainage work, regarding the capacity of small tile. I even remember 

 to have heard one ardent advocate claim that a two-inch tile would carry all 

 the water from forty acres. That same man put in miles of drains on that 

 principle. A failure by using too small tile, is likely to be followed by the 

 other extreme of using too large tile. 



